Means and method of dressing grinders



May lO, 1932.

A. L. DE LEEUW MEANS AND METHOD OF DRESSING GRINDERS 7 Filed Dec. 13, 1927 4 Sheets-Sheet v Emma;

May 10, 1932. A. 1.. DE LEEUW MEANS AND METHOD OF DRESSING GRINDERS Filed Dec. 13. 1927 4 Sheets-Sheet 2 3.5 flbtometf I May 10,- 1932. 35 LEEUw 1,857,142

MEANS AND METHOD OF DRESSING GRINDERS Filed Deb. 13.1927 4 Sheets-.Sheet 3 avweutoz 42012,

' A. L. DE LEEUW 1,857,142

MEANS AND METHOD OF DRESSING GRINDERS May 10, 1932.

Filed Dec. 13. 1927 4 Sheets-Sheet 4 Leas THAN [0' WHEEL gvweutoz alien wow MM $W Patented May 10, 1932 UNITED STATES PATENT OFFICE ADOLPH .L. DE LEEUW, OF PLAINFIELD, NEW JERSEY, ASSIGNOR OF ONE-HALF TO ALBERT F. NATHAN, OF NEW YORK, N. Y.

' MEANS AND METHOD OF DRESSING GRINDERS Application filed December 13, 1927. Serial No. 239,704.

This invention relates to an improved method and apparatus for dressing the working faces of grind wheels and other. abrading elements to a predetermined form or contour 5 by a generating process and is so contrived as to be especially suitable for dressing the wheel of the grinding machine disclosed in my Patent No. 1,666,737, dated April 17, 1928.

Other objects and advantages will be in part indicated in the following description and in part rendered apparent therefrom in connection with the annexed drawings.

To enable others skilled in the art so fully to apprehend the underlying features hereof that they may embody the same in the various ways contemplated by this invention,

drawings, depicting a preferred typical construction have been annexed as a part of 2 this disclosure and, in such drawings, like characters of reference denote corresponding parts throughout all the views, of which Figure 1 is a fragmentary plan view of an improved gear grinding machine showing the wheel truing device as it is used. Fig. 2

is an enlarged plan View, partly in section,

of the wheeltruing device showing the driv-' ing mechanism therefor. Fig. 3 is a vertical sectional view of a gear grinding machine showing the means for advancing the abrasive wheel and truing device during the dressing operation. Fig. 4 is an enlarged portion of the abrasive wheel showing diagrammatically the path of one of the reciprocating diamond points. Fig. 5 is a plan view of the reciprocating diamond points and the method of dressing the abrasive wheel so that a radial section thereof is in exact conformity with an accurately ground gear tooth. Fig. 6 is a representation of a modified form of wheel dressin g device mounted on the base of the machine and the grinding wheel adapted to be moved into engagement therewith, as more fully described in my above indicated patent.

(5 As shown in Figs. 1 and 3, the wheel dressing unit D is slidably mounted on a revolving table 10 which is made integral with a large stem 11. The stem 11 is translatably but not rotatably mounted in the sleeve 12 which is [a driven by suitable worm gearing (not shdwn) located in the base of the =machine. For a more complete and detailed description of the machine, reference may be had to my copending application filed March 23, 1926, Serial N umber 96,706. Sufiice it to say that the table be developed by a grinding operation, the

blanks must roll with respect to the properly contoured periphery of the grinding wheel. To this end the blanks are mounted on one end of a spindle 13, carried by an adjustable bracket 131. On the other end of the spindle is mounted a master pinion 14. in mesh with a master gear 15, having a relatively prime number of teeth. It is suflicient in this disclosure to assume there is but one grindingwheel and that it initially coincides with a given tooth of the prime gear. If N represents the number of teeth on the prime gear 15, and n represents the number of teeth on the master pinion 14, then after the prime gear has rotated n times the original tooth of the prime gear will again be in contact with the original tooth of the master pinion. Thus, it will be seen that since the grind wheel 16 is mounted directly over the prime gear and its contour in cross section is in exact conformity with a given tooth on the prime gear 15, n revolutions of the table 10 will cause the abrasive wheel to grind every tooth of the gear blank. As hereinbefore mentioned, the table, while rotating, is fed downwardly very slowly. Consequently the path of the grinding wheel is in the form of a helix having closely spaced convolutions. Hence, if the operation is repeated, such convolutions in the aggregate will equal the width of the gear-blank.

As shown in Fig. 3, a stack of gear blanks may be mounted on the spindle 13 and if there are a plurality of spindles such for example, as shown in Fig. 1, there is constant gradual wear on the abrasive wheel. It has been found desirable, therefore, to at- One end of a flexible non-elastic strap 35 tach to the machine an automatic wheel truing device to maintain absolute accuracy in the inding of any quantity of gears.

Smce the abrading wheel must be initially formed and, from time to time, re-formed to Therefore, if a given pinion be re laced bya rack, the grinding wheel woul likewise develop straight sided'teeth in a rack-blank and, conversely, if the rack-blank be regarded as an abrader and if its teeth were formed with accurate straight sides, then it would dress the abrasive wheel into a tooth-contour conforming accurately to the master tooth of the prime gear 15. Inasmuch as an abrasive rack is impractical, it is proposed to employ two diamond points each representing one side' of the hypothetical abrasive rack and continuously to reciprocate those diamond points rapidly in straight lines to simulate the straight sides of the hypothetical abrasive rack. Such points will serve to dress the grinding wheel accurately to its proper contour.

The actual construction may now be understood by referring to Figs. 1 and 2 in which 29 is a bracket, mounted on the plate 17 so as to permit oscillatory movement, and having secured thereto, at its lower edge, a plate 30; the front edge 31 of which represents the pitch line of the hypothetical rack before mentioned. Fixed to the plate 17 is a second plate 32, having a stepped marginal portion; the edges 33 and 34 of which are arcuately formed to represent a portion of the pitch circle and base circle, respectively, of the prime gear 15.

By holclin the surface 31 of the rack plate 30 firmly against the surface 33 of the plate 32 (in such a manner that no tangential movement of the rack plate 30 takes place with respect to the arcuate plate 32) and giving the plate 30 a rolling movement, the resulting effect is the same as though the two members were a.true rack and a gear. I

This invention proposes a novel means for holding the plate 30 against the plate 32 Without relying on frictional contact alone, or resorting to the costly operation of machining rack teeth and ear teeth on the two plates.

This is accomplished in the manner now to be described.

is securely fastened to the stepped plate 32 by means of a drive pin 36. The strap extends at a tangent to the base circle 34 along a line which ordinarily would be the normal pressure angle between a rack and gear of this size. The other end is fastened to a pin 37 projecting from the plate 30. A similar strap 38 has one end fastened to the plate 32,

'a slightly larger one. The periphery of the large disc will serve to represent the pitch circle of a gear wheel and the periphery of the smaller disc serving to represent the base circle. By holding the cord taut and at the same time unwrapping it from the disc, any point on the cord will trace a true and exact involute curve. If two cords are wound in opposite directions around the disc and have their outer ends fastened to the ends of a straight edge contacting with the periphery of the larger disc, it is at once apparent that as one cord is unwrapped the other winds up, and a given point on the straight edge will therefore trace an exact involute curve also. Since one cord cannot unwind any faster than the other cord winds up, the straight edge is held tightly against the pitch circle the plates to function in a manner identical with the action of a rack and gear connection. 1

- As shown in Figs. 2 and 3, a rocking motion maybe imparted to the plate 30 to cause it to roll about the periphery or pitch circle of the plate 32 without relative tangential movement, which is the converse of a gear rolling in a rack. I

The diamond -,.points 41 and 42 are securely held in slide rods 43 and 44 slidably mounted on the bracket 29 and in a plane containing the axis of the rinding wheel. The slide rods are inclinef in conformity with the sides of a rack tooth and have rack teeth out on the inner side of oneend for engagement with the teeth of a wide faced pinion 45. The other extremities of these slide rods are ofi'set and provided with diaaxis. A helical gear 47, secured to the motor bracket 29. Integral with the shaft 48 are worm gears 49 and 50, the worm 49 drivin a worm-wheel 51 which carries the link 52 pivoted eccentric thereto. The other end of the link 52 is pivoted to a lever 58 connected to a shaft 54, the upper end ofwhich has the wide faced pinion. mounted thereon. Thus, it will be seen that rotary movement of the shaft 48 imparts an oscillatory movement to' the pinion 45 and a resultant reciprocatory movement to the diamond points 41 and 42 in the' direction of the sides of an imaginary rack tooth.

Oscillatory movements are imparted to the diamond points by means of the gear trains 50, 55, 56, and 57; the gear 57 carrying one end of the eccentrically pivoted link 58, the other end of which is pivoted to the plate 17. Rotary movement of the shaft 48 consequently imparts an oscillatory movement to the bracket 29 relative to the plate 17. Bolts 29 co-acting with slots 29 serve to clamp the bracket 29 to the plate 17 to prevent any lifting or overturning movement thereof.

To insure that the diamond points do not retrace the same path, before the entire abrad-.

ing surface of the grinding wheel has been dressed to shape, the speed of the reciprocatory gear train and the oscillatory gear train is such that the latter runs slower than the former to cause the result shown diagrammatically in Fig. 4.

Figs. 4 and 5 show diagrammatically the action of the diamond points on the abrading wheel; the figures being enlarged several times. As the slide-bar 44 moves in the direction of the arrow d, the slide bar 43 moves in the opposite direction, and conversely, and

since the abrading wheel is turning in the of the tool are very minute and over-lap as indicated at J, Fig. 4. As hereinbefore stated, the reciprocation of the diamond points are in straight lines congruent with the sides of a rack, and since the bracket 29, carrying the slide rods 43 and 44, is given an oscillatory movement to simulate the relative movements'between a rack and gear, the diamond points consequently follow a path indicated by the arrows g and k. In this manner, the proper form is maintained on the abrasive wheel at all times since the diamond points are kept in close contact with the periphery of the grinding wheel and continuously remove any projecting portions thereof.

Due to the wear on the abrasive wheel, caused by the grinding operation, the diamond points must necessarily be advanced slightly in order to dress the wheel properly. This may be accomplished in various ways, one of which is shown in Fig. 3. .On the under side of the bracket 29, a shaft 23 is threaded through a nut 60 fixed to the bracket. The shaft is rotated by means of a wormwheel 24 meshed with a worm 25 mounted on the upper end of the shaft 26. The lower end of the shaft 26 carries a six station wheel 27, which, as the table 10 rotates, is periodically engaged by a fixed stop 28 projecting from the base of the machine.

Means is provided for advancing the grinding Wheel 16 to compensate for the infinitesimal amount removed by the action of the diamond points, which means consists of a nut 19 fixed to the under side of the plate 17 through which a shaft 20 is threaded. The outer end of the shaft carries a gear 21, which is driven bya pinion 22 mounted on the shaft 23. As will be apparent from Figs. 2 and 3, the gears 22 and 23 are so ratioed that the bracket 29 is advanced substantially twice as fast as the slide 17 and thus the diamond points are kept in contact with the grinding wheel during the continuous advance of the wheel toward the gear-blanks. Although only a single grinding attachment has been referred to as carried by the table 10, it is to be understood that, to increase production, the table may be equipped with a plurality of such attachments. Fig. 1 shows two grinding attachments carried by the table and with this arrangement each rotalines, is a duplicate of the unit shown in full lines, hereinbefore described and detailed description thereof is deemed unnecessary. T o

enable two grinding attachments to be secured upon the table, the attachments are preferably located at one side of the axis of Y the table, as shown in Fig. 1. With this arrangement, the dressing attachment D is positioned at an angle with respect to the center line of the abrading wheel (Figs. 1, 2 and 5) in order that the correct tooth angle be formed on the wheel to coincide with the underlying tooth of the prime gear 15.

The operation of the machine is as follows :The operator loads the machine with out further attention from the attendant.

During the grinding operation, the dressing attachment automatically maintains the grind wheel in proper form in the manner hereinbefore set forth.

From the foregoing, it will be perceived s that this invention provides a unique and accurate means for automatically maintaining a grinding wheel in a desired form. Obviously, the same result may be accomplished by various other arrangements utilizing the same principle. As shown in Fig. 6, the

' dressing attachment may be mounted on a bracket 75 secured to the base of the machine. A straight tooth rack 76 is slidably mounted in its lower end and acarriage 77 slidably mounted in its upper end; the slideways being accurately parallel with a straight line tangential to the pitch circle of the prime gear 15. The carriage 75 carries the diamond points and the mechanism for reciprocating them in a manner similar to the manner pre-- viously described. This tangential relation may accurately be secured by straight edge plate 78 fixed to the rack 7 6 and brought to bear peripherally against a ring 79 accurately formed to correspond to the pitch circle of the prime gear 15. The shaft. 80 terminating in gears 81 and 82 (accurately meshing with appropriateracks) cause the carriage 75 to counterpart all of the movements of the rack 76 or the carriage 75 and the rack 76 may be constituted as a single element slidably mounted on the bracket 75. With "this arrangement, the grinding wheel is radually shifted horizontally towards the region of the reciprocating diamond points until it has completely attained the appropriate contour;

- the prime gear 15 being in a state of motion should be, and are intended to be, comprehended within the meaning and range of equivalency of the following claims.

Having thus revealed this invention, I claim as new and desire to secure the following combinations and elements, or equivalents thereof, by Letters Patent-of United States i 1. The method of dressing the periphery of an abrasive wheel into an adopted involute tooth-section, consisting in rotating said wheel about its own axis; causing a diamond point rapidly to reciprocate in a radial plane of the wheel and in a straight-line at an angle coincident with' a side of an adopted racktdoth; and simultaneously laterally rolling the path of said diamond point about a center ment with a dressin lying on the base circle of said adopted tooth section while acting on said wheel.

2. A wheel dressing device combining a plate member having one ed e shaped to correspond with the pitch circ e of a given gear; a base'member having one edge thereof engaging the edge of said plate member; means to hold said-members in close contact;

a grindingwheel mounted on one of said members; a diamond point reciprocably mounted on the other of said members and adapted to true said wheel; and means simultaneously to reciprocate said diamond and to cause relative rolling movement between the members.

3. A grinding machine comprising a grinding wheel and a dressing mechanism therefor; said mechanism comprising two slides angularly disposed and carrying diamonds at their extremities; and means for simultaneously oscillating and repeatedly reciprocating said slides to cause said diamonds to develop a predetermined contour on said grinding wheel.

4. A grinding machine combining a grind wheel; a rotatable support for said grind wheel; a wheel truing device mounted upon said support and adapted to dress said wheel; a work-support; means actuated by the movement of said rotatable support to feed said wheel toward said work-support; and means actuated in timed relation with the feed of said wheel to maintain said truing device in engagement therewith.

5. The method of dressing the periphery of a grind wheel to the form of an annular gear tooth which consists of continuously engaging the grind wheel with a dressing element; reciprocating the dressing element in the plane of the tooth-section across a portion of the grind wheel periphery; rotating said wheel to present new areas thereof to the dressing element and simultaneously effecting relative lateral rolling movements between the wheel and the dressing element to cause said dressing element to develop a predetermined contour on the peripheral portion of the grind wheel.

6. The method of dressin an abrading element to the form of an a opted gear tooth which consists of engaging the abrading eleelement; rapidly reciprocating the dressing element radially of and in the general plane of the adopted gear tooth of the abradmg elementacross a portion thereof; moving one of said elements in a direction transverse to the plane of the tooth section formed on the abrading ele-- ment to present new areas to the dressing element and simultaneously effecting a relative lateral movement between said elements while in dressing relationship to develop a predetermined shape on said abradingelement.

7. The method of dressing the periphery of an abrasive wheel into an adopted involute tooth-section, consisting in rotating said wheel about its own axis and simultaneously swinging it bodily about a central transverse axis into engagement with a diamond point;

, rapidly reciprocating the diamond in a radial plane of the said wheel and in a straight line at an angle coincident with the side of an adopted rack tooth; and simultaneously effecting relative lateral rolling movements between the wheel and the diamond point todevelop a predetermined contour on said wheel.

8. A grinding wheel dressing mechanism comprising a grinding wheel; two slides an-' gularly disposed and carrying diamonds at their extremities, and means including two power actuated eccentrics for simultaneously oscillating and repeatedly reciprocating said slides to cause said diamonds to develop a predetermined contour on said wheel.

9. A machine of the class described combining a grind wheel, said grind wheel in Y section having the contour of a gear tooth;

a dressing element movable radially of said wheel and in the plane of the tooth section; power means including an eccentrically mounted link member for causing a relative rolling movement between the grind wheel' and said dressing element to develop the face movement between said dressing element in a plane containing the axis of said wheel to develop the face of the tooth portion of said wheel in a straight line; and means to reciprocate said dressing element in a direction parallel to the face of the tooth portion of said wheel, including an eccentric device driv-. en from said power means and operatively connected with said dressing element.

11. A dressing device for truing a grind wheel combining a pair of diamond holders slidably mounted and angularly disposed A the path of movement of the dressing element in the plane of the tooth-section while in dressing engagement therewith, and rotating the grind wheel to present unfinished areas to the dressing element. I

13. A grinding machine comprising a grind wheel and a dressing mechanism therefor, said mechanism comprising two slides angularly disposed and carrying diamonds at their extremities; means for simultaneously oscillating and repeatedly reciprocating said slides to cause said diamonds to develop a predetermined contour on said wheel; power operated means for feeding the grind-wheel toward the work to be ground; and means actuated in timed relation with the feed of said wheel to maintain said dressing mechanism in engagement therewith.

14. A wheel dressing device combining a plate member having one edge shaped to correspond with the pitch circle of a given gear; a base member having one edge thereof engaging the edge 'ofsaid plate member; flexile means for holding said members in close contact; a grinding wheel mounted on one of said members; a diamond point reciprocably mounted on the other of said members and adapted to true said wheel; and means including a prime mover adapted simultaneously'to reciprocate said diamond and to cause {)elative rolling movement between the memers.

15. A grinding machine comprising a grinding wheel and a dressing mechanism therefor; said mechanism comprising two slides angularly disposed and carrying diamonds at their extremities; a movable suporting bracket for said slides; and means or eifecting simultaneously a combined oscillatory and reciprocatory motion to said slides to cause said diamonds to develop a predetermined contour on said grinding wheel.

In'witness whereof, I hereunto subscribe my name.

ADOLPH L. DE LEEUW.

with'respect to each other, diamonds mounted 1 in said holders and adapted to engage portions of the grind wheel; a movable supporting bracket for said holders; means for reciprocating said holders radially of said wheel; and means for imparting simultaneously an oscillatory movement to said bracket to cause;

said diamonds to develop a predetermined contour on said 'wheel'. I

12. The herein described method of dressing a portion of a grind wheel into an adopted tooth-section which consists in applying a 

